Voltage-gated potassium currents from individual GFP⁺ TK23 cells.

<p><b>A,</b> Representative example of delayed rectifier current (upper panel) evoked by depolarizing current steps (lower panel; steps range from −120 mV to +80 mV; Vm = −60 mV). <b>B</b>, Peak (open square) and steady-state (filled square) current-voltage plot for the cell shown in <b>A</b>. <b>C,</b> Representative example of the protocol used to determine K⁺ reversal potential. K⁺ current in upper panel, protocol in lower panel (steps range from −100 mV to −20 mV; pre-pulse to +20 mV; Vm = −60 mV). <b>D</b>, Current-voltage relationship from data in <b>C</b>, illustrating values taken at 2 ms (filled circle) and 20 ms (open circle) after the end of the conditioning pulse to +20 mV. Reversal potential is noted as the point at which the two lines intersect (dashed gray line). <b>E,</b> Another example of delayed rectifier current (upper panel) evoked by short depolarizing current steps followed by a step to −50 mV for use in calculating K⁺ activation (lower panel; steps range from −120 mV to +100 mV; tail current step to −50 mV (arrow); Vm = −60 mV). <b>F</b>, Average (±sem) activation curve for all neurons (n = 35). Data obtained from the tail current (arrow in <b>E</b>), were used for the calculation of K⁺ channel activation.